The present disclosure relates generally to the field of latch mechanisms and particularly to a latch mechanism utilized in an aircraft. More particularly, the present disclosure relates to a latch mechanism which operates in response to a pressure change on at least one side of a barrier in an aircraft to allow a panel associated with the barrier to release upon a given set or range of pressure conditions.
By way of review, a variety of latch mechanisms have been developed to maintain panels, doors and other structures in a closed position. The reference to panels, doors and other structures relates to the use of latch mechanisms to retain a first body, such as a panel relative to a second body, such as a frame. With regard to the example of panels, a panel includes one portion which might be rotatably hinged or otherwise movably retained on a corresponding structure such as a frame. The panel serves to close or cover at least a portion of an opening defined by the frame for a variety of purposes including providing a barrier to prevent passage through the opening.
A variety of latch mechanisms have been developed to facilitate the movement or “blowout” of a panel relative to the frame. Such blowout latch mechanisms have been developed by Hartwell Corporation, assignee of the present disclosure, to facilitate disengagement of a panel from a frame or other structure under a set or range of “blowout” conditions. For example, if a pressure differential develops on opposite sides of a barrier or within an area at least partially housed or contained by the panel, the pressure differential will rise to a point where the panel may be forcibly removed, disengaged or “blown out” from the frame by forces associated with the pressure differential. Under these conditions, it is desirable to set the blowout force at a desired level or range so that premature disengagement of the panel from the primary structure does not occur. In this situation, the blow out load level can be set so that a predetermined pressure differential disengages the panel from the primary structure to protect and preserve the integrity of the frame and any related structures and devices.
In some situations, it would be desirable to maintain a panel in a closed position under one level or range of pressure conditions yet release the panel under a second range or set of conditions. Such level or range may or may not overlap or may be discrete ranges or, in fact, points. The panel in such a situation generally is in an environment where the pressure on either side of the panel is generally equalized. The panel may include a sealing structure to prevent the unwanted or abrupt passage of air there through. However, the pressure on either side of the panel is generally equal.
One example of the use of such a panel in a well-known environment is the use of a panel in a pressurized cabin such as in an aircraft. The panel is employed as a barrier to separate the flight crew, passengers and/or cargo into discrete areas. Such a panel may be used between the flight deck and passenger compartment as well as perhaps between the passenger compartment and corresponding storage area which is not occupied by passengers. In the situation in which the panel is used on an aircraft in which the cabin is pressurized, it may be desirable to maintain the panel in a closed position for many situations but allow the panel to be opened when the pressure differential between the two compartments changes. Such a pressure differential may occur in the case where cabin pressure drops in the cargo compartment due to a leak or other loss of pressure. Under these circumstances, it might be desirable to allow the cabin pressure to generally equalize to avoid or minimize damage which might result from the pressure differential.
Similarly, in a situation where a panel is positioned between the flight deck and the passengers, it may be desirable to release the panel and equalize the pressure between the flight deck and passenger area. In the situation in which the panel is positioned between the flight deck and passenger area, it might be desirable to allow the panel to disengage, rather than having the door structurally fail as a result of the unequal pressure differentials.
For example, the panel to the flight deck generally is maintained in a closed and latched position while in flight to maintain privacy and security of the flight crew. This prevents the passage of passengers or terrorists into the flight deck area. Increased latching strength is required in order to prevent a passenger or terrorist from forcibly opening the panel. However, in a situation in which pressure is lost in the passenger compartment, it may be desirable to allow the panel to release in order to prevent the panel from being forcibly removed from the structure by the pressure differential. This would help prevent injury to passengers if the panel were forcibly removed from the frame and expelled into the passenger compartment. By allowing the panel to release in response to the pressure differential between the flight deck and passenger compartment, the panel will open thereby providing increased safety. Similarly, if the pressure differential occurs as a result of loss of pressure in the flight deck, the panel will be allowed to disengage the frame, yet be retained thereon, to provide pressure equalization to prevent injury to the flight crew and equipment.
With the foregoing in mind, it would be desirable to provide a method, system and apparatus to provide unlatching of the door latch under a range or set of pressure differential circumstances.
Additional features of the disclosure will become apparent to those skilled in the art upon consideration of the following detailed description of the disclosed embodiments.